Copyright.
Postman's Sort (tm) is a computer program owned by Robert Ramey
and is protected by United States copyright laws and international
treaty provisions. Therefore,
you must treat the software just like
any other copyrighted material such as book or musical recording
except that you may one copy of the program
solely for backup or archival purposes. You may
not copy the written materials accompanying the program.

Just like a book
means that this software may be used by any number of people and
may be freely moved from one computer location to another so long as
there is no possibility of it being used at one location while
it is being used at another. In the same way that two different
people in two different places cannot read the same book at the
same time, neither may the software be used by two different
people in two different places at the same time without violating
Robert Ramey's copyright.
U.S. Government Restricted Rights

This program and documentation are provided with Restricted
Rights.
Use, duplication, or disclosure by the Government is subject to
restrictions as set forth in sub-paragraph (c)(1)(ii) of the Rights in
Technical Data and Computer Software clause at DFARS 252.227-7013
or sub-paragraphs (c)(1) and (2) of the Commercial Computer Software --
Restricted Rights at 48 CFR 52.227-19, as applicable.
Manufacturer is Robert Ramey, Santa Barbara, CA 93110.